Electricity

Components and Symbols of Electric Circuit

Series and Parallel Circuits


Series Circuit

This circuit has two bulbs, two batteries, wires and a switchl. The bulbs are connected in series. We call this a series circuit.






 Parallel Circuit





This circuit has two bulbs, two batteries, wires and a switch.The bulbs are connected in parallel. We call this a parallel circuit.









What is the effect on the bulbs in the following circuits when one of the switches is switched off ?

The Solar System

The solar system is made up of the Sun and the objects that orbit around it. These include EIGHT planets, and their satellites (moons).
(Note: Pluto, once the 9th planet, it is no longer recognised as one of the planets in the solar system)

There are also asteroids, meteoroids, comets and drifting particles called interplanetary dust.
The solar system was formed about 4.6 billion years ago.

The Sun 

The centre of our solar system is the sun, which is a star. It is a gigantic ball of hot gas which gives off heat and light energy. It is about 150 million kilometres away from Earth.The sun's gravity keeps all the planets and other objects in the solar system travelling around it.


Planets and moon

The planets do not produce their own energy. They reflect the heat and light of the sun. All the planets are surrounded by layers of gases called atmospheres.



The EIGHT planets of our Solar System

Mercury is the smallest planet, and is closest to the sun. It is extremely hot.




Venus is the second planet from the Sun. Clouds of poisonous gases hide the surface of Venus. Winds blow across the smooth, dry surface. There are volcanoes in a few places.





Earth is the third planet from the sun, in between Venus (named after the Roman goddess of love) and Mars. It is the only planet known to support life.

Mars the planet fourth from the Sun, and known as 'the red planet'.



The largest planet is Jupiter, which is fifth from the sun. It consists of gas and liquid. 

Saturn, sixth from the sun, is the second largest planet. It has thousands of thin rings around it, made up of particles of rock and ice.

                                    

Uranus, seventh planet from the sun. It is surrounded by clouds of blue-green gas.



Neptune is the eighth planet from the Sun. It is the fourth largest planet and is one of the gas giants planets.

 

Pollution

 Air pollution

Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere.

The atmosphere is a complex dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
  

Water pollution

Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans and groundwater).

Water pollution affects plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and populations, but also to the natural biological communities.

Land pollution

Land pollution is the degradation of Earth's land surfaces often caused by human activities and their misuse of land resources. It occurs when waste is not disposed properly. Health hazard disposal of urban and industrial wastes, exploitation of minerals, and improper use of soil by inadequate agricultural practices are a few factors. The Industrial Revolution set a series of events into motion which destroyed natural habitats and polluted the environment, causing diseases in both humans and other species of animals.